1. Field of the Invention
The present invention relates to a novel liquid-crystalline compound and to an organic semiconductor film and an organic semiconductor device containing the compound.
The present invention relates to a compound with a thiadiazole group introduced into both ends of the aromatic ring therein, and to an organic semiconductor film and an organic semiconductor device containing the compound.
2. Background Art
Recently, thin-film devices such as typically OFET (organic field-effect transistor) devices using an organic semiconductor material have become specifically noted.
In particular, forming an integrated circuit with an organic semiconductor, if possible, could make it possible to form the integrated circuit inexpensively, as compared with the existing production process of forming integrated circuits using silicon.
In integrated circuits generally used at present, employed is a configuration called CMOS (complementary metal oxide semiconductor). In this configuration, the gate electrode of the n-channel transistor and the gate electrode of the p-channel transistor are connected to each other and the drain electrode of the n-channel transistor and the drain electrode of the p-channel transistor are connected to each other. The configuration is characterized by strong resistance to noise and low power consumption.
CMOS requires both the p-type semiconductor that assumes the role of hole transport and the n-type semiconductor that assumes the role of electron transport. When one compound could assume the two roles, then the production process could be thereby simplified. Examples of the compound of the type are described, for example, in Patent Reference 1.
In order to attain suitable carrier transport characteristics of an organic semiconductor, an important matter is configuration control of organic semiconductor molecules. One method of configuration control thereof comprises controlling the configuration of organic semiconductor molecules via a liquid-crystal phase not having a crystal-analogous layer structure or columnar structure. In fact, there are seen many publications relating to organic semiconductors having a liquid-crystal phase (for example, Patent Reference 2).
There are known some compounds, each one of which has a liquid-crystal phase and has both a hole-transport capability and an electron-transport capability by itself (for example, Patent Reference 3).
However, the compounds described in the above-mentioned Patent References 1 to 3 have absorption in the visible region. Accordingly, in some cases, they may be often unfavorable for use in transistors for display devices to be used under visible light.
There are known some compounds that does not absorb visible light and has both a hole-transport capability and an electron-transport capability by itself. But that compounds have low level electron mobility and hole mobility (for example, Nonpatent Reference 1).